### ASA 126th Meeting Denver 1993 October 4-8

## 3aAO3. Estimating vertical and horizontal wave-number temperature spectra
of a buoyant thermal plume.

**John Oeschger
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*Univ. of Rhode Island, Dept. of Phys., Kingston, RI 02881
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**Louis Goodman
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*Naval Undersea Warfare Ctr., Newport, RI 02841
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Acoustic scattering from a buoyant thermal plume described by the
far-field Born approximation results in a simple relationship between the
scattered pressure field and the scattering field; namely, the two are Fourier
transform pairs. For media variability, such as the buoyant plume where the
spatial variability is larger than the Fresnel radius, wave-front curvature
must be included to describe experimental results adequately. Under conditions
where Taylor's hypothesis is satisfied (the time variability is entirely due to
the advection at a constant velocity of spatial variability), the effects of
wave-front curvature on the scattering process can be removed. Data are
collected for simultaneous multiple bistatic scattering experiments in common
and antiparallel scattering directions for the unstable and turbulent plume.
Results include an estimation of the vertical and horizontal wave-number
temperature spectra of the buoyant plume.